Commit | Line | Data |
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906568c9 TG |
1 | /* |
2 | * linux/kernel/time/tick-common.c | |
3 | * | |
4 | * This file contains the base functions to manage periodic tick | |
5 | * related events. | |
6 | * | |
7 | * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de> | |
8 | * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar | |
9 | * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner | |
10 | * | |
11 | * This code is licenced under the GPL version 2. For details see | |
12 | * kernel-base/COPYING. | |
13 | */ | |
14 | #include <linux/cpu.h> | |
15 | #include <linux/err.h> | |
16 | #include <linux/hrtimer.h> | |
17 | #include <linux/irq.h> | |
18 | #include <linux/percpu.h> | |
19 | #include <linux/profile.h> | |
20 | #include <linux/sched.h> | |
21 | #include <linux/tick.h> | |
22 | ||
f8381cba TG |
23 | #include "tick-internal.h" |
24 | ||
906568c9 TG |
25 | /* |
26 | * Tick devices | |
27 | */ | |
f8381cba | 28 | DEFINE_PER_CPU(struct tick_device, tick_cpu_device); |
906568c9 TG |
29 | /* |
30 | * Tick next event: keeps track of the tick time | |
31 | */ | |
f8381cba TG |
32 | ktime_t tick_next_period; |
33 | ktime_t tick_period; | |
d3ed7824 | 34 | int tick_do_timer_cpu __read_mostly = -1; |
f8381cba | 35 | DEFINE_SPINLOCK(tick_device_lock); |
906568c9 | 36 | |
289f480a IM |
37 | /* |
38 | * Debugging: see timer_list.c | |
39 | */ | |
40 | struct tick_device *tick_get_device(int cpu) | |
41 | { | |
42 | return &per_cpu(tick_cpu_device, cpu); | |
43 | } | |
44 | ||
79bf2bb3 TG |
45 | /** |
46 | * tick_is_oneshot_available - check for a oneshot capable event device | |
47 | */ | |
48 | int tick_is_oneshot_available(void) | |
49 | { | |
50 | struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev; | |
51 | ||
52 | return dev && (dev->features & CLOCK_EVT_FEAT_ONESHOT); | |
53 | } | |
54 | ||
906568c9 TG |
55 | /* |
56 | * Periodic tick | |
57 | */ | |
58 | static void tick_periodic(int cpu) | |
59 | { | |
60 | if (tick_do_timer_cpu == cpu) { | |
61 | write_seqlock(&xtime_lock); | |
62 | ||
63 | /* Keep track of the next tick event */ | |
64 | tick_next_period = ktime_add(tick_next_period, tick_period); | |
65 | ||
66 | do_timer(1); | |
67 | write_sequnlock(&xtime_lock); | |
68 | } | |
69 | ||
70 | update_process_times(user_mode(get_irq_regs())); | |
71 | profile_tick(CPU_PROFILING); | |
72 | } | |
73 | ||
74 | /* | |
75 | * Event handler for periodic ticks | |
76 | */ | |
77 | void tick_handle_periodic(struct clock_event_device *dev) | |
78 | { | |
79 | int cpu = smp_processor_id(); | |
3494c166 | 80 | ktime_t next; |
906568c9 TG |
81 | |
82 | tick_periodic(cpu); | |
83 | ||
84 | if (dev->mode != CLOCK_EVT_MODE_ONESHOT) | |
85 | return; | |
86 | /* | |
87 | * Setup the next period for devices, which do not have | |
88 | * periodic mode: | |
89 | */ | |
3494c166 | 90 | next = ktime_add(dev->next_event, tick_period); |
906568c9 | 91 | for (;;) { |
906568c9 TG |
92 | if (!clockevents_program_event(dev, next, ktime_get())) |
93 | return; | |
94 | tick_periodic(cpu); | |
3494c166 | 95 | next = ktime_add(next, tick_period); |
906568c9 TG |
96 | } |
97 | } | |
98 | ||
99 | /* | |
100 | * Setup the device for a periodic tick | |
101 | */ | |
f8381cba | 102 | void tick_setup_periodic(struct clock_event_device *dev, int broadcast) |
906568c9 | 103 | { |
f8381cba TG |
104 | tick_set_periodic_handler(dev, broadcast); |
105 | ||
106 | /* Broadcast setup ? */ | |
107 | if (!tick_device_is_functional(dev)) | |
108 | return; | |
906568c9 TG |
109 | |
110 | if (dev->features & CLOCK_EVT_FEAT_PERIODIC) { | |
111 | clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC); | |
112 | } else { | |
113 | unsigned long seq; | |
114 | ktime_t next; | |
115 | ||
116 | do { | |
117 | seq = read_seqbegin(&xtime_lock); | |
118 | next = tick_next_period; | |
119 | } while (read_seqretry(&xtime_lock, seq)); | |
120 | ||
121 | clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT); | |
122 | ||
123 | for (;;) { | |
124 | if (!clockevents_program_event(dev, next, ktime_get())) | |
125 | return; | |
126 | next = ktime_add(next, tick_period); | |
127 | } | |
128 | } | |
129 | } | |
130 | ||
131 | /* | |
132 | * Setup the tick device | |
133 | */ | |
134 | static void tick_setup_device(struct tick_device *td, | |
135 | struct clock_event_device *newdev, int cpu, | |
136 | cpumask_t cpumask) | |
137 | { | |
138 | ktime_t next_event; | |
139 | void (*handler)(struct clock_event_device *) = NULL; | |
140 | ||
141 | /* | |
142 | * First device setup ? | |
143 | */ | |
144 | if (!td->evtdev) { | |
145 | /* | |
146 | * If no cpu took the do_timer update, assign it to | |
147 | * this cpu: | |
148 | */ | |
149 | if (tick_do_timer_cpu == -1) { | |
150 | tick_do_timer_cpu = cpu; | |
151 | tick_next_period = ktime_get(); | |
152 | tick_period = ktime_set(0, NSEC_PER_SEC / HZ); | |
153 | } | |
154 | ||
155 | /* | |
156 | * Startup in periodic mode first. | |
157 | */ | |
158 | td->mode = TICKDEV_MODE_PERIODIC; | |
159 | } else { | |
160 | handler = td->evtdev->event_handler; | |
161 | next_event = td->evtdev->next_event; | |
162 | } | |
163 | ||
164 | td->evtdev = newdev; | |
165 | ||
166 | /* | |
167 | * When the device is not per cpu, pin the interrupt to the | |
168 | * current cpu: | |
169 | */ | |
170 | if (!cpus_equal(newdev->cpumask, cpumask)) | |
171 | irq_set_affinity(newdev->irq, cpumask); | |
172 | ||
f8381cba TG |
173 | /* |
174 | * When global broadcasting is active, check if the current | |
175 | * device is registered as a placeholder for broadcast mode. | |
176 | * This allows us to handle this x86 misfeature in a generic | |
177 | * way. | |
178 | */ | |
179 | if (tick_device_uses_broadcast(newdev, cpu)) | |
180 | return; | |
181 | ||
906568c9 TG |
182 | if (td->mode == TICKDEV_MODE_PERIODIC) |
183 | tick_setup_periodic(newdev, 0); | |
79bf2bb3 TG |
184 | else |
185 | tick_setup_oneshot(newdev, handler, next_event); | |
906568c9 TG |
186 | } |
187 | ||
188 | /* | |
189 | * Check, if the new registered device should be used. | |
190 | */ | |
191 | static int tick_check_new_device(struct clock_event_device *newdev) | |
192 | { | |
193 | struct clock_event_device *curdev; | |
194 | struct tick_device *td; | |
195 | int cpu, ret = NOTIFY_OK; | |
196 | unsigned long flags; | |
197 | cpumask_t cpumask; | |
198 | ||
199 | spin_lock_irqsave(&tick_device_lock, flags); | |
200 | ||
201 | cpu = smp_processor_id(); | |
202 | if (!cpu_isset(cpu, newdev->cpumask)) | |
203 | goto out; | |
204 | ||
205 | td = &per_cpu(tick_cpu_device, cpu); | |
206 | curdev = td->evtdev; | |
207 | cpumask = cpumask_of_cpu(cpu); | |
208 | ||
209 | /* cpu local device ? */ | |
210 | if (!cpus_equal(newdev->cpumask, cpumask)) { | |
211 | ||
212 | /* | |
213 | * If the cpu affinity of the device interrupt can not | |
214 | * be set, ignore it. | |
215 | */ | |
216 | if (!irq_can_set_affinity(newdev->irq)) | |
217 | goto out_bc; | |
218 | ||
219 | /* | |
220 | * If we have a cpu local device already, do not replace it | |
221 | * by a non cpu local device | |
222 | */ | |
223 | if (curdev && cpus_equal(curdev->cpumask, cpumask)) | |
224 | goto out_bc; | |
225 | } | |
226 | ||
227 | /* | |
228 | * If we have an active device, then check the rating and the oneshot | |
229 | * feature. | |
230 | */ | |
231 | if (curdev) { | |
79bf2bb3 TG |
232 | /* |
233 | * Prefer one shot capable devices ! | |
234 | */ | |
235 | if ((curdev->features & CLOCK_EVT_FEAT_ONESHOT) && | |
236 | !(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) | |
237 | goto out_bc; | |
906568c9 TG |
238 | /* |
239 | * Check the rating | |
240 | */ | |
241 | if (curdev->rating >= newdev->rating) | |
f8381cba | 242 | goto out_bc; |
906568c9 TG |
243 | } |
244 | ||
245 | /* | |
246 | * Replace the eventually existing device by the new | |
f8381cba TG |
247 | * device. If the current device is the broadcast device, do |
248 | * not give it back to the clockevents layer ! | |
906568c9 | 249 | */ |
f8381cba TG |
250 | if (tick_is_broadcast_device(curdev)) { |
251 | clockevents_set_mode(curdev, CLOCK_EVT_MODE_SHUTDOWN); | |
252 | curdev = NULL; | |
253 | } | |
906568c9 TG |
254 | clockevents_exchange_device(curdev, newdev); |
255 | tick_setup_device(td, newdev, cpu, cpumask); | |
79bf2bb3 TG |
256 | if (newdev->features & CLOCK_EVT_FEAT_ONESHOT) |
257 | tick_oneshot_notify(); | |
906568c9 | 258 | |
f8381cba TG |
259 | spin_unlock_irqrestore(&tick_device_lock, flags); |
260 | return NOTIFY_STOP; | |
261 | ||
262 | out_bc: | |
263 | /* | |
264 | * Can the new device be used as a broadcast device ? | |
265 | */ | |
266 | if (tick_check_broadcast_device(newdev)) | |
267 | ret = NOTIFY_STOP; | |
906568c9 TG |
268 | out: |
269 | spin_unlock_irqrestore(&tick_device_lock, flags); | |
f8381cba | 270 | |
906568c9 TG |
271 | return ret; |
272 | } | |
273 | ||
274 | /* | |
275 | * Shutdown an event device on a given cpu: | |
276 | * | |
277 | * This is called on a life CPU, when a CPU is dead. So we cannot | |
278 | * access the hardware device itself. | |
279 | * We just set the mode and remove it from the lists. | |
280 | */ | |
281 | static void tick_shutdown(unsigned int *cpup) | |
282 | { | |
283 | struct tick_device *td = &per_cpu(tick_cpu_device, *cpup); | |
284 | struct clock_event_device *dev = td->evtdev; | |
285 | unsigned long flags; | |
286 | ||
287 | spin_lock_irqsave(&tick_device_lock, flags); | |
288 | td->mode = TICKDEV_MODE_PERIODIC; | |
289 | if (dev) { | |
290 | /* | |
291 | * Prevent that the clock events layer tries to call | |
292 | * the set mode function! | |
293 | */ | |
294 | dev->mode = CLOCK_EVT_MODE_UNUSED; | |
295 | clockevents_exchange_device(dev, NULL); | |
296 | td->evtdev = NULL; | |
297 | } | |
d3ed7824 TG |
298 | /* Transfer the do_timer job away from this cpu */ |
299 | if (*cpup == tick_do_timer_cpu) { | |
300 | int cpu = first_cpu(cpu_online_map); | |
301 | ||
302 | tick_do_timer_cpu = (cpu != NR_CPUS) ? cpu : -1; | |
303 | } | |
906568c9 TG |
304 | spin_unlock_irqrestore(&tick_device_lock, flags); |
305 | } | |
306 | ||
cd05a1f8 | 307 | static void tick_suspend(void) |
6321dd60 TG |
308 | { |
309 | struct tick_device *td = &__get_cpu_var(tick_cpu_device); | |
310 | unsigned long flags; | |
311 | ||
312 | spin_lock_irqsave(&tick_device_lock, flags); | |
cd05a1f8 | 313 | clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_SHUTDOWN); |
6321dd60 TG |
314 | spin_unlock_irqrestore(&tick_device_lock, flags); |
315 | } | |
316 | ||
cd05a1f8 | 317 | static void tick_resume(void) |
6321dd60 TG |
318 | { |
319 | struct tick_device *td = &__get_cpu_var(tick_cpu_device); | |
320 | unsigned long flags; | |
321 | ||
322 | spin_lock_irqsave(&tick_device_lock, flags); | |
323 | if (td->mode == TICKDEV_MODE_PERIODIC) | |
324 | tick_setup_periodic(td->evtdev, 0); | |
cd05a1f8 TG |
325 | else |
326 | tick_resume_oneshot(); | |
6321dd60 TG |
327 | spin_unlock_irqrestore(&tick_device_lock, flags); |
328 | } | |
329 | ||
906568c9 TG |
330 | /* |
331 | * Notification about clock event devices | |
332 | */ | |
333 | static int tick_notify(struct notifier_block *nb, unsigned long reason, | |
334 | void *dev) | |
335 | { | |
336 | switch (reason) { | |
337 | ||
338 | case CLOCK_EVT_NOTIFY_ADD: | |
339 | return tick_check_new_device(dev); | |
340 | ||
f8381cba TG |
341 | case CLOCK_EVT_NOTIFY_BROADCAST_ON: |
342 | case CLOCK_EVT_NOTIFY_BROADCAST_OFF: | |
343 | tick_broadcast_on_off(reason, dev); | |
344 | break; | |
345 | ||
79bf2bb3 TG |
346 | case CLOCK_EVT_NOTIFY_BROADCAST_ENTER: |
347 | case CLOCK_EVT_NOTIFY_BROADCAST_EXIT: | |
348 | tick_broadcast_oneshot_control(reason); | |
349 | break; | |
350 | ||
906568c9 | 351 | case CLOCK_EVT_NOTIFY_CPU_DEAD: |
79bf2bb3 | 352 | tick_shutdown_broadcast_oneshot(dev); |
f8381cba | 353 | tick_shutdown_broadcast(dev); |
906568c9 TG |
354 | tick_shutdown(dev); |
355 | break; | |
356 | ||
6321dd60 | 357 | case CLOCK_EVT_NOTIFY_SUSPEND: |
cd05a1f8 | 358 | tick_suspend(); |
6321dd60 TG |
359 | tick_suspend_broadcast(); |
360 | break; | |
361 | ||
362 | case CLOCK_EVT_NOTIFY_RESUME: | |
363 | if (!tick_resume_broadcast()) | |
cd05a1f8 | 364 | tick_resume(); |
6321dd60 TG |
365 | break; |
366 | ||
906568c9 TG |
367 | default: |
368 | break; | |
369 | } | |
370 | ||
371 | return NOTIFY_OK; | |
372 | } | |
373 | ||
374 | static struct notifier_block tick_notifier = { | |
375 | .notifier_call = tick_notify, | |
376 | }; | |
377 | ||
378 | /** | |
379 | * tick_init - initialize the tick control | |
380 | * | |
381 | * Register the notifier with the clockevents framework | |
382 | */ | |
383 | void __init tick_init(void) | |
384 | { | |
385 | clockevents_register_notifier(&tick_notifier); | |
386 | } |